The EF24mm f/2.8 IS USM is one of the first wide-angle single-focus lenses to feature an image stabilisation (IS) mechanism, which achieves the equivalent effect of four shutter speed-stops faster. This diminutive and lightweight lens is such a breeze to use, thanks to its ring ultrasonic motor (USM) and optimized autofocus algorithms for quick yet silent focusing, a full-time manual focus, and a circular aperture for soft-focus images. A function to recognize if a normal shot or a panning shot is being taken allows the Image Stabilizer mode to switch to the appropriate mode for the shot.